Ceramic packages have been used to contain a light-emitting element, such as a high brightness light-emitting diode (LED) and a semiconductor laser diode (LD).
A conventional ceramic package includes a substrate on which a light emitting element is to be mounted and a frame defining an opening provided on the substrate. The substrate has wiring conductors electrically connected to an external power source. A light emitting element is electrically connected to the wiring conductors by wire bonding. Electricity is externally supplied to the light emitting element via the bonding wires to cause the device to emit light. The emitted light is released outside through the opening directly and after reflected on the surface of the substrate or inner circumferential surface of the frame. Therefore, the shape and composition of the substrate surface and the inner circumferential surface of the frame are greatly influential on the light emission efficiency of a light emitting device.
It is known to use high reflection metal to make the frame of the above described light emitting device. In this case, because the ceramic substrate and the metallic frame have different thermal expansion coefficients, the frame can separate from the substrate due to the heat generated from the light emitting element. To prevent the separation, a ceramic frame plated with metal is proposed (e.g., Patent Document 1). Silver (Ag) is known as a high reflection plating material. In using Ag, about 90% reflectance, relative to barium sulfate, of wavelengths of about 460 nm is achieved. However, the reflectances of wavelengths shorter than about 460 nm are low, averaging 77% in a wavelength range of from 250 nm to 800 nm.    Patent Document 1: JP 2004-228531A